Sample extraction apparatus with micro elution bed design

ABSTRACT

An apparatus for extracting an analyte from a liquid sample having a container with an entrance, an exit, and a passage therebetween for passage of a liquid sample containing an analyte, the container having a full diameter bed region and a reduced diameter bed region. The container includes a layered construction extending across the passage, having from top to bottom one or more of: (i) an upper flow distributor/support layer, (ii) an upper compression layer, (iii) an extraction layer of microparticulate extraction medium adjacent to the layer (ii), and (iv) a lower compression layer located adjacent to the extraction layer (iii), optionally including one or more air gap layers. At least some of the layers are located in the full diameter bed region, and some of the layers are located in the reduced diameter bed region. The apparatus may have a plurality of containers arranged in an array and/or in series so as to provide multi-stage filtration or extraction.

RELATED APPLICATIONS

This application claims priority and is entitled to the earliest effective filing date of U.S. non-provisional application Ser. No. 15/086,029, filed on Mar. 30, 2016. Specifically, this application is a continuation application and so claims the benefit pursuant to 35 U.S.C. § 120 of prior filed and co-pending U.S. non-provisional patent application Ser. No. 15/086,029, filed on Mar. 30, 2016, which itself is a continuation-in-part application of U.S. non-provisional application Ser. No. 14/718,065, filed on May 20, 2015, which claims priority pursuant to 35 U.S.C. § 119(e) to and is entitled to the filing date of U.S. provisional application Ser. No. 62/000,759, filed on May 20, 2014. The contents of the aforementioned applications are incorporated herein by reference.

BACKGROUND

The present invention relates to microcolumns for extraction of an analyte from a liquid sample, and particularly extraction of an analyte from biological fluids.

Accurate and inexpensive detection of analytes present in liquid samples, for example in biological fluids, such as blood and urine, is important to health care. Tests for analytes in blood and urine are conducted to monitor the health of patients, detect the presence of disease conditions, and monitor for the use of illegal or restricted drugs. For example, doctors, when administering drugs such as anti-arrythymics, asthmatic drugs, insulin, and anticoagulants, check the drug content of the blood to regulate the dosages of the patient. Drugs that can be abused, such as heroin, marijuana, cocaine, and codeine, can be tested to determine abuse of the drug, such as by employees and by athletes.

A technique used for detection of analytes includes selectively extracting the analyte from the biological fluid onto a solid media. The analyte is then removed from the solid media by a suitable elution liquid, and tests are conducted to determine whether the analyte is present in the eluent liquid. These tests are conducted using Gas Chromatography-Mass Spectrometry or Liquid Chromatography-Mass Spectrometry.

Extraction columns have been used in the past. For example, particulate silica has been used as the solid media in a column. In addition, media has been sandwiched between frits in a column with a single diameter cylindrical shape. Although these prior art devices can be effective, it is desirable to improve on these devices, and their impact in the overall process and their downstream environmental impact. It is desirable that the extraction device improve process throughput, remove a very high percentage of the analyte from the sample, be transportable, storable without damage, and be inexpensive. Moreover, it is desirable that any such device be compatible with existing automated equipment, and not leach into the biological or other fluid samples the eluent liquid or any compound that could interfere with the analytical results. Likewise, it is desirable to minimize the media bed volume and associated dead volumes to lower the volume of the wash eluent liquid. By minimizing the liquid volume, a more concentrated sample is obtained for analysis, and the sensitivity of the test is enhanced. High yields from the sample fluid with minimum elution volumes can be obtained by maintaining uniform flow through the extraction media, with no channeling and no dead volume.

SUMMARY

Embodiments of the present invention include an apparatus for extraction of an analyte from a liquid sample. The apparatus includes a container having an entrance, an exit, and a passage therebetween for passage of the liquid sample containing an analyte therethrough, said container having a full diameter bed region and a reduced diameter bed region. The apparatus includes a layered construction having a top and a bottom extending across the passage, comprising from top to bottom: (i) an upper flow distributor/support layer, (ii) an upper compression layer, (iii) an extraction layer of microparticulate extraction medium adjacent to the layer (ii), and (iv) a lower compression layer located adjacent to the extraction layer (iii), where the (i) upper flow distributer and (ii) upper compression layer are located in the full diameter bed region, the (iii) extraction layer and (iv) lower compression layer are located in the reduced diameter bed region. In additional embodiments, the apparatus may include a seven layered construction including (i) an upper flow distributor, (ii) an upper compression layer, (i′) a middle flow distributor, (ii′) a middle compression layer in the reduced diameter bed region, (iii) an extraction layer of microparticulate extraction medium adjacent to the layer (ii′), (iv) a lower compression layer adjacent to layer (iii), and (v) optionally, a lower flow distributor, wherein layers (i), (ii), (i′), and (ii′) are located in the full diameter bed region, and layers (iii)-(v) may be located in the reduced diameter bed region.

In one embodiment, the apparatus has one or more air gap layers. In one embodiment an air gap layer is located in the reduced-diameter bed region. The air gap layer of a further embodiment has a height that ranges from ½ the diameter of the reduced diameter bed region to 4 times the diameter of the reduced diameter bed region. In yet a further embodiment, an air gap layer is located between layer (i′) and layer (ii′).

The ratio between the effective area of the full diameter bed region and the reduced diameter bed region may also vary. The effective area of the full diameter bed region is A_(F)=πr_(F) ², where r_(F) is the radius of an interior surface of the container in the full diameter bed region, and the effective area of the reduced diameter bed region is A_(r)=πr_(r) ² where r_(r) is the radius of an interior surface of the container in the reduced diameter bed region. The ratio between the effective bed area of the full diameter bed region and the effective area of the reduced diameter bed region ranges from about 10:1 to 1.5:1. In one embodiment the ratio between the effective area of the extraction media to the effective area of the upper compression layer is about 1:10. In a further embodiment the ratio between the effective area of the extraction media to the effective area of the upper compression layer is about 1:4. In another embodiment, the ratio between the effective area of the full diameter bed region and the effective area of the reduced diameter bed region is about 4:1.

The extraction media may also be tailored to work with a particular analyte. In one embodiment the extraction media has a number average particle size of about less than 20 μm. In a further embodiment, the extraction media has a number average particle size of about less than 10 μm.

The present apparatus may have a plurality of containers arranged in an array, optionally having a collection plate with a corresponding array of wells.

In a further embodiment, the apparatus has dual barrels or is configured in two stages, again whether with a single container or multiple containers per stage. The top barrel or first stage is equipped with a filtration system to remove unwanted impurities as the analytical samples are passed through the top barrel. Upon passing through the top barrel, the analytes of interest may be caught by the bottom barrel or second stage column filled with desired amount of sorbent, enabling relatively cleaner extracts with relatively smaller elution volumes.

Further embodiments of the invention are directed to methods of using the present apparatus, and kits including the present apparatus.

The present invention and its multiple embodiments are described further below. Of course, variations on these described embodiments will become apparent to those of ordinary skill in the art upon reading the present description, and thus, one of skill in the art would recognize suitable combinations and variations.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate aspects of the present invention. In such drawings:

FIG. 1A is a schematic perspective view of the exterior of the present apparatus. FIG. 1B is an enlarged schematic cross-sectional side view of one embodiment of the layers used in the present apparatus.

FIG. 2A is a cross-sectional side view of a conventional microcolumn M. FIG. 2B is a cross-sectional side view of an alternative embodiment of the present apparatus. FIG. 2C is a cross-sectional side view of a further alternative embodiment of the present apparatus with one or more ribs 50 on the exterior. FIG. 2D is a partial perspective view of the lower narrow diameter portion of the present apparatus, showing the ribs used in a luer tip system. FIG. 2E is an exterior side view of the present apparatus including the luer tip at the exit end thereof.

FIG. 3 is a schematic cross-sectional side view of a further alternative embodiment of the layers used in the present apparatus which include an air gap.

FIG. 4A is exemplary data obtained with the present apparatus using 10 pg/ml of dopamine. FIG. 4B is exemplary data obtained with the present apparatus using 10 pg/ml of dopamine. FIG. 4C is exemplary data obtained with the present apparatus using 10 pg/ml of norepinephrine. FIG. 4D is exemplary data obtained with the present apparatus using 10 pg/ml of norepinephrine. FIG. 4E is exemplary data obtained with the present apparatus using 10 pg/ml of epinephrine. FIG. 4F is exemplary data obtained with the present apparatus using 10 pg/ml of epinephrine.

FIG. 5A is exemplary data obtained with the present apparatus using 100 pg/ml dopamine. FIG. 5B is exemplary data obtained with the present apparatus using 100 pg/ml of dopamine. FIG. 5C is exemplary data obtained with the present apparatus using 100 pg/ml of norepinephrine. FIG. 5D is exemplary data obtained with the present apparatus using 100 pg/ml of norepinephrine. FIG. 5E is exemplary data obtained with the present apparatus using 100 pg/ml of epinephrine. FIG. 5F is exemplary data obtained with the present apparatus using 100 pg/ml of epinephrine.

FIG. 6A is calibration curve of buprenorphine extracted from urine with the present apparatus. FIG. 6B is calibration curve of norbuprenorphine extracted from urine with the present apparatus.

FIG. 7A is a schematic cross-sectional side view of a further alternative embodiment of the layers used in the present apparatus which include an air gap. FIG. 7B is a schematic cross-sectional side view of a further alternative embodiment of the layers used in the present apparatus which include multiple air gaps.

FIG. 8A is a schematic cross-sectional side view of a further alternative embodiment of the layers used in the present apparatus here included only in the upper full diameter bed region. FIG. 8B is a schematic cross-sectional side view of a further alternative embodiment of the layers used in the present apparatus again included only in the upper full diameter bed region, with an optional frit layer.

FIG. 9A is a schematic cross-sectional side view of a further alternative embodiment of the layers used in the present apparatus here included only in the intermediate reduced diameter bed region. FIG. 9B is a schematic cross-sectional side view of a further alternative embodiment of the layers used in the present apparatus again included only in the intermediate reduced diameter bed region, with an optional air gap.

FIG. 10A is a perspective view of an exemplary embodiment of the present apparatus having dual barrels or configured in two stages. FIG. 10B is an enlarged partial cross-sectional side view of the upper barrel or first stage thereof. FIG. 10C is an enlarged partial cross-sectional side view of the lower barrel or second stage thereof.

FIG. 11A is a perspective view of a further exemplary embodiment of the present apparatus having dual barrels or configured in two stages. FIG. 11B is an enlarged partial cross-sectional side view of the upper barrel or first stage thereof. FIG. 11C is an enlarged partial cross-sectional side view of the lower barrel or second stage thereof.

The above described drawing figures illustrate aspects of the invention in at least one of its exemplary embodiments, which are further defined in detail in the following description. Features, elements, and aspects of the invention that are referenced by the same numerals in different figures represent the same, equivalent, or similar features, elements, or aspects, in accordance with one or more embodiments.

DETAILED DESCRIPTION

The present invention is directed to an extraction apparatus that meets the needs of: improving downstream environmental impact and process throughput; removing a very high percentage of the analyte from the sample; transportability; storage without damage; price point; compatibility with existing automated equipment; leaching characteristics; minimization of the media bed volume and associated dead volumes; and enhancing sensitivity and uniformity of flow through the extraction media.

The present apparatus is useful for extracting an analyte from a liquid sample and comprises a container, typically a microcolumn, having an entrance, an opposed exit, and a passage therebetween for passage of a liquid sample containing an analyte therethrough.

Referring to FIGS. 1A and 1B, the microcolumn 12 of the present apparatus 10 has at least two regions in the passage 23 of the analyte: an area having a full diameter bed (aka the “full diameter bed region”, shown in FIGS. 1A and 1B as 30) and an area having a reduced diameter bed (aka the “reduced diameter bed region”, shown in FIGS. 1A and 1B as 31). As used herein, “diameter bed area” is measured by the surface area of a horizontal cross-section of the interior cavity of the container. Therefore, for a cylindrical container the diameter bed area is the area of the circle (πr²) whose diameter (=2r) extends from one side of the interior cavity of the container to the other side of the interior cavity. The diameter bed area may also be referred to as the “effective area” of a particular layer.

Within the passage 23 in the reduced diameter bed region 31 is a layer of a microparticulate extraction media. Extraction media 14 may include any known sorbent and a variety of particles. The sorbent particles employed in the apparatus include any particulate matter that is capable of having at least one substance, either target or interfering, adhered thereto. Illustrative examples of sorbent particles that may be employed in the present invention include, but are not limited to: ion exchange sorbents; reversed phase sorbents; and normal phase sorbents. More particularly, the sorbent particles may be an inorganic material such as SiO₂ or an organic polymeric material such as poly(divinylbenzene). In some embodiments of the present invention, the sorbent particles may be treated with an organic functional group such as a C₂-C₂₂, preferably C₈-C₁₈ functional group. In one embodiment, the sorbent of the extraction media includes silica based particles (such as silica based carboxylic acids), diatomaceous earth particles, polymeric based particles, mono-dispersed silica and polymeric particles, and/or carbon graphite particles. The media is selected for extracting the analyte from the liquid sample. A suitable silica extraction media is described in U.S. Pat. No. 4,650,714, which is incorporated herein by reference. A preferred microparticulate silica extraction media is available from Avantor Performance Materials (previously known as J.T. Baker Chemical Company) of Phillipsburg, N.J., and is sold under their catalog number 7049-01.

The extraction media 14 has a small particle size having a number average particle size of less than about 40 microns, less than about 30 microns, less than about 25 microns, less than about 20 microns, less than about 15 microns, less than about 10 microns, or less than about 5 microns. In one embodiment, the extraction media has a number average particle size of less than about 20 microns, or more preferably less than about 10 microns. In addition, the extraction media does not have to be homogenous, but rather a different extraction media can be used in a single bed, or the apparatus can include multiple beds of extraction media for extracting different analytes from samples.

The extraction media 14 is sandwiched between at least two compression layers. In one embodiment, the diameter bed area of the extraction media is lower than the diameter bed area of the upper compression layer, such that the ratio of the effective area of the upper compression layer to the effective area of the extraction media layer is about 10 to 1, about 9 to 1, about 8 to 1 about 7 to 1 about 6 to 1, about 5 to 1, about 4 to 1, about 3 to 1, about 2 to 1, or about 1.5 to 1. In one embodiment, the ratio of the effective area of the upper compression layer to the effective area of the extraction media layer is about 4 to 1.

The extraction media may be loosely packed (where the sorbent is loosely sandwiched between the compression layers and free to move) or a compacted extraction media bed (where the extraction media is compacted between the two layers, or has relatively little additional possible space between particles).

The extraction media is sandwiched between either the upper compression layer 18 a and lower compression layer 18 b or the middle compression layer 18 c and lower compression layer 18 b, and compress the extraction media there between. Upper compression layer 18 a is located in full diameter bed region 30, middle compression layer 18 c may be located in either the full diameter bed region 30 or reduced diameter bed region 31, and lower compression layer 18 b is located in reduced diameter bed region 31. In one embodiment only two compression layers are used. In one embodiment, at least three compression layers are used.

The compression layers are sufficiently porous that the liquid sample can flow therethrough, and are formed from a flexible material. One or more of the compression layers may be flat, spherical, or optimally shaped to suit the fluid flow through the apparatus (such as a truncated cone, prismatic, truncated pyramid, etc.). FIG. 3 shows an embodiment where the middle and lower compression layers (18 c and 18 b, respectively) are spherical. A mixture of shapes of compression layers may be used in a single microcolumn.

The narrow bore sandwich design pairs with the low dead volume column design for function. The chief purpose of compression layers 18 is to hold the extraction media 14 in place and compressed as a thin extraction layer. In one embodiment, one or more of the compression layer(s) has a pore size less than the particle size of the extraction media and functions as a flow rate limiter. They are sufficiently porous that the liquid sample can flow therethrough, and are composed of a flexible, hydrophilic material. The compression layer is preferably formed of a spongy, glass fiber, having no binder.

A suitable compression layer comprises a glass microfiber media made of analytically clean material. Suitable materials, which are available from Whatman Specialty Products, Inc. of Fairfield, N.J., include borosilicate glass fibers that are analytically clean and include no binder. This material, when purchased, has a smooth side and a rough side, where the smooth side is of lower porosity than the rough side. Preferably, it is the smooth side that is placed in contact with the microparticles of extraction layer 14. Other suitable materials include frits and filters, such as polymer (e.g., polypropylene or polyethylene) frit materials. Said frits or filters may be cylindrical, die cut, or spherical, having a diameter to fit the interior cavity of the column; for instance, in the full diameter portion or in the reduced diameter portion.

Preferably compression layers 18 are resilient or “spongy” to hold the microparticles in place. In one aspect, the pore size for the compression layers is less than 10 microns, less than 5 microns, or less than 3 microns. Compression layers 18 generally are of the same thickness, having a thickness typically of from about 0.1 mm to about 3.25 mm, about 0.25 mm to about 3.25 mm, about 0.5 mm to about 3.0 mm, about 0.75 mm to about 3 mm, about 0.25 mm to about 2.5 mm, about 0.25 mm to about 2 mm, about 0.25 mm to about 1.5 mm, about 0.25 mm to about 1.25 mm, about 0.25 mm to about 1.0 mm, about 0.1 mm to about 0.75 mm, or about 0.1 mm to about 0.5 mm. In one aspect the compression layer(s) have a thickness of about 0.5 mm.

This is in contrast to the prior art microelution columns, which are made with cylindrical syringe barrel tubes, or funnel shaped sample reservoirs (see e.g., US 2006/0163163). Although some of these microelution columns have reduced dead volume after the bed, these designs do not address the ratio between the effective area of the upper compression layer compared to the effective area of the extraction media layer.

Reducing the effective area (πr²) of the extraction media bed about 4−1 in relation to the effective area of the upper compression layer leads to a corresponding reduced volume of sorbent material and reduced dead volumes for the reagent.

Flow distributors 16, which are formed of a flexible mesh material, help provide uniform flow of the sample through the column, and physically retain the compression layers and microparticulate material in place in the column. Preferably, the mesh is 200 mesh or smaller, (i.e., has a mesh number of 200 or higher). In aspects of this embodiment, the mesh number is 150 or higher, 170 or higher, 200 or higher, 250 or higher, 270 or higher, 325 or higher, or 400 or higher. The mesh may be made of any flexible bio-inert material. It one embodiment it is made of Polyphenelyne Sulfide (PPS), Polytetrafluoroethylene (PTFE), Polyether ether Ketone (PEEK), Polyoxymethylene (POM), Ethylene Propylene Diene (EPDM), a Fluorinated elastomer (FKM), a Perfluoro elastomer (FFKM), polysulfone (PSU), Ethylene Tetrafluoroethylene (ETFE), Polypropylene (PP), (Poly)Chlorotrifluoroethylene (PCTFE/CTFE), polystyrene, high density polyethylene, polycarbonate, nylon, polyethylene terephthalate (PET), silicon, rubber, or polyester. In aspects of this embodiment it is made of polypropylene, or alternatively, polytetrafluoroethylene. A suitable material is available from Tetko, Inc. of Briarcliff Manor, N.Y., under catalog number 5-420134.

In one embodiment the microcolumn 12 also includes an upper mesh flow distributor 16 a above the upper compression layer 18 a for support, and, optionally, a middle flow distributor 16 b and/or a lower flow distributor 16 c. In one embodiment, the flow distributors may be layered or molded in the housing above and below the compression layer(s), sandwiching the compression layers 18 and the layer of extraction media 14 therebetween. The flow distributors 16 hold the extraction media 14 and the compression layers 18 in the reduced diameter bed region 31 of the microcolumn 12 and help distribute flow of the liquid sample to avoid channeling. As shown in the embodiment of FIG. 1B, the upper flow distributor 16 a is located in the full diameter bed region 30, the middle flow distributor 16 b is also located in the full-diameter bed region 30 and the lower flow distributor 16 c, if used, seats in the lower portion of the column in the reduced diameter bed region 31. In one embodiment, the upper flow distributor 16 a is sized so that it is held in the bore of microcolumn 12 by a compression fit. Similarly, the other flow distributor layer(s) may also be sized for a compression fit.

Due to the combination of the narrow bore extraction media and the compression layer sandwich, rapid extraction of an analyte from a fluid can be obtained, with the apparatus being configured for very small volumes of elution liquid on the order of about 0.025 mL to about 0.25 mL, about 0.025 mL to about 0.2 mL, about 0.025 mL to about 0.15 mL, about 0.025 mL to about 0.100 mL, down from 0.5 mL to 1.5 mL. This smaller elution volume fits directly into autosampler trays for automation. Smaller volumes eliminate concentration steps and vial transfers and associated cross contamination fails. In addition, the extraction device of the present invention is inexpensive to use and manufacture, is stable during storage and transportation, and is compatible with existing automated equipment. The experimental data below displays the effective improvement in performance of a clinical assay done using regular Cerex columns versus the Narrow Bore version (the presently disclosed columns).

An apparatus 10 for extracting an analyte from a liquid sample is again shown in FIG. 1A. As shown in FIG. 1A, the apparatus 10 comprises the microcolumn 12, which serves as a container for an extraction sandwich system. In one embodiment, microcolumn 12 has generally a tubular configuration, and has entrance 20, opposed exit 22, and passage 23 therebetween. Passage 23, which is also referred to as a central bore, contains the extraction system. Passage 23 has two regions, upper full diameter bed region 30 and lower reduced diameter bed region 31. The exit 22 may optionally be located in a separate region 33, with a “tip” configuration.

The various layers may be located adjacent to each other, and may or may not be in direct contact with the surrounding layers. That is, with reference to FIG. 3, there may be one or more Air Gaps 301 between two layers which are deliberately located to prevent dripping or capillary flow and allow for the transfer of the column to an appropriate receiving vessel or plate. For instance, in one embodiment, there is an Air Gap layer 301 between the middle flow distributor 16 b and the middle compression layer 18 c. That is, in one embodiment, there may be an air gap between the layers that straddle the transition from the full diameter bed region 30 to the reduced diameter bed region 31. In another embodiment there may be a strategic Air Gap 301 located after the lower compression layer 18 b but before the optional lower distributor layer 16 c.

In one embodiment, the Air Gap is positioned at or below the top edge of the reduced diameter bed region, and may have a height ranging from ½ of the diameter of the reduced diameter bed region to 4 times the diameter of the reduced diameter bed region. In aspects of this embodiment, the height of the air gap may be from, e.g., about ½ to about 1 times, about ½ to about 1.5 times, about ½ to about 2 times, about ½ to about 2.5 times, about ½ to about 3 times, about ½ to about 3.5 times, about ½ to about 4 times, about 1 to about 1.5 times, about 1 to about 2 times, about 1 to about 2.5 times, about 1 to about 3 times, about 1 to about 3.5 times, about 1 to about 4 times, about 1.5 to about 2 times, about 1.5 to about 2.5 times, about 1.5 to about 3 times, about 1.5 to about 3.5 times, about 1.5 to about 4 times, about 2 to about 2.5 times, about 2 to about 3 times, about 2 to about 3.5 times, about 2 to about 4 times, about 2.5 to about 3 times, about 2.5 to about 3.5 times, about 2.5 to about 4 times, about 3 to about 3.5 times, about 3 to about 4 times, or about 3.5 to about 4 times, the diameter of the reduced diameter bed region.

When placed strategically at the inlet to the reduced diameter bed region, the air gap prevents the unassisted capillary flow of certain classes of solvents or samples from bridging the gap for capillary transfer down to the next layer and then through the media bed. The air gap is particularly useful in areas with smaller diameters because the strength of the air gap is based on the surface tension between the liquid flowing through the apparatus and the gas located in the air gap.

The gap height may vary by the intended analytes to be tested, and might not be there at all. The Air Gap is particularly useful in a method where the compression layers are wet or preconditioned before the test sample is added to the microcolumn.

The structure of tip region 33 is not particularly limited and in one embodiment may be cylindrical or conical. Tip region 33 may have the same diameter as the reduced diameter bed region 31 or a smaller diameter than the reduced diameter bed region 31. In one embodiment, the tip region 33 has the same footprint as the reduced diameter bed region 31; in another embodiment, the footprint of the tip region 33 has a differently shaped footprint than the reduced diameter bed region 31. In one embodiment, tip region 33 is optionally in the form of a luer tip or similar, which allows apparatus 10 to be used with conventional automated extraction apparatuses, which are designed to receive an extraction column having a luer tip.

In another embodiment, FIG. 2C provides a vertical cross-section of the present apparatus 10 with one or more ribs 50 on the exterior, though with all interior layers or features removed for simplicity. FIG. 2D is a partial perspective view of the lower narrow diameter portion of the present apparatus 10, showing the ribs 50 used in a luer tip system. FIG. 2E is a side view of the present apparatus 10 including the luer tip system at the exit end of the present apparatus.

A liquid sample flows in the direction of arrow 26 shown in FIG. 1B through the passage 23.

The portion of microcolumn 12 above the extraction sandwich system serves as a reservoir for the liquid sample, from which an analyte is to be extracted, and also a reservoir for a washing liquid, and an eluent liquid.

In one embodiment, the extraction system includes a four-layer sandwich construction with: (i) an upper flow distributor/support, (ii) an upper compression layer, (iii) an extraction layer, and (iv) a lower compression layer, where the upper flow distributer is located in the full diameter bed region and the upper compression layer, the extraction layer and the lower compression layer are located in the reduced diameter bed region.

In one embodiment, the extraction system is comprised of a five-layer sandwich construction, including (i) an upper flow distributor, (ii) a cylindrical or fabric compression layer, (iii) a spherical or cylindrical frit as a compression layer, (iv) the microparticulate extraction medium, and (v) a spherical or cylindrical frit as a lower compression layer. Layers (i)-(ii) would reside in the full diameter bed region, where layers (iii)-(v) would reside in the reduced diameter bed region.

In one embodiment, the extraction system is comprised of a six-layer sandwich construction, including (i) an upper flow distributor, (ii) a cylindrical or fabric compression layer, (iii) a lower flow distributor, (iv) a spherical or cylindrical frit as a compression layer, (v) the microparticulate extraction medium, and (vi) a spherical or cylindrical frit as a lower compression layer. Layers (i)-(iii) would reside in the full diameter bed region, where layers (iv)-(vi) would reside in the reduced diameter bed region. In one embodiment as shown in FIG. 1B, the extraction system is comprised of a seven-layer sandwich construction, that includes (i) upper flow distributor 16 a, (ii) upper compression layer 18 a, (iii) middle flow distributor 16 b, (iv) middle compression layer 18 c in the reduced diameter bed region 31, (v) extraction layer 14 of microparticulate extraction medium, (vi) lower compression layer 18 b, and optionally (vii) lower flow distributor/support 16 c which may be molded as part of the container. In this embodiment, layers (i)-(iii) may be located in the full diameter bed region, and layers (iv)-(vii) may be located in the reduced diameter bed region. Alternatively, the division between full diameter and reduced diameter may occur between layers (ii) and (iii). Additional layers may be added.

In a further embodiment as shown in FIG. 3, the extraction system is comprised of an eight-layer sandwich construction, that includes: (i) upper flow distributor 16 a, (ii) upper compression layer 18 a, (iii) middle flow distributor 16 b, (iv) air gap layer 301, (v) middle compression layer 18 c in the reduced diameter region 31, (vi) extraction layer 14 of microparticulate extraction medium, (vii) lower compression layer 18 b, and optionally (viii) lower flow distributor/support 16 c which may be molded as part of the container. In this embodiment, layers (i)-(iii) may be located in the full diameter bed region, and layers (iv)-(viii) may be located in the reduced diameter bed region. Alternatively, the division between full diameter and reduced diameter may occur between layers (ii) and (iii). Additional layers may be added.

In a still further embodiment as shown in FIG. 7A, the extraction system is comprised of a seven-layer sandwich construction, that includes: (i) upper flow distributor 16 a, (ii) upper compression layer 18 a, (iii) middle flow distributor 16 b, (iv) middle compression layer 18 c in the reduced diameter region 31, (v) air gap layer 314 in the place of extraction layer 14 (FIGS. 1B and 3), (vi) lower compression layer 18 b, and optionally (vii) lower flow distributor/support 16 c which may be molded as part of the container. In this embodiment, layers (i)-(iii) may be located in the full diameter bed region, and layers (iv)-(vii) may be located in the reduced diameter bed region. Alternatively, the division between full diameter and reduced diameter may occur between layers (ii) and (iii). Additional layers may be added.

In a still further embodiment as shown in FIG. 7B, the extraction system is comprised of an eight-layer sandwich construction, that includes: (i) upper flow distributor 16 a, (ii) upper compression layer 18 a, (iii) middle flow distributor 16 b, (iv) air gap layer 301, (v) middle compression layer 18 c in the reduced diameter region 31, (vi) air gap layer 314 in the place of extraction layer 14 (FIGS. 1B and 3), (vii) lower compression layer 18 b, and optionally (viii) lower flow distributor/support 16 c which may be molded as part of the container. In this embodiment, layers (i)-(iii) may be located in the full diameter bed region, and layers (iv)-(viii) may be located in the reduced diameter bed region. Alternatively, the division between full diameter and reduced diameter may occur between layers (ii) and (iii). Additional layers may be added.

In connection with the alternative embodiments of FIGS. 7A and 7B, there may again be one or more Air Gaps 301, 314 between two layers which are deliberately located to prevent dripping or capillary flow and allow for the transfer of the column to an appropriate receiving vessel or plate. For instance, in one such embodiment, there is an Air Gap layer 314 between the middle compression layer 18 c and the lower compression layer 18 b in the place of the extraction layer 14 (FIGS. 1B and 3), though it could be in addition to such extraction layer 14. Or there is an Air Gap layer 301 between the middle flow distributor 16 b and the middle compression layer 18 c as well, so as to have effectively two air gaps separated by at least one material layer, further contributing to the prevention of dripping or capillary flow. That is, in one embodiment, there may be an air gap between the layers that straddle the transition from the full diameter bed region 30 to the reduced diameter bed region 31 and/or between the layers of the reduced diameter bed region 31. In any such embodiments the height of thickness of any particular air gap, just as the material layers, can vary depending on the context, such that all drawings are to be understood as illustrative and not to scale and thus non-limiting.

In a still further embodiment as shown in FIG. 8A, the extraction system is comprised of a three-layer sandwich construction, that includes: (i) upper flow distributor 16 a, (ii) upper compression layer 18 a, and (iii) middle flow distributor 16 b. In this embodiment, layers (i)-(iii) may be located in the full diameter bed region, with no layers located in the reduced diameter bed region. Alternatively, the division between full diameter and reduced diameter may occur between layers (ii) and (iii). Additional layers may be added.

In a still further embodiment as shown in FIG. 8B, the extraction system is comprised of a four-layer sandwich construction, that includes: (i) upper flow distributor 16 a, (ii) upper compression layer 18 a, (iii) optional frit 17, and (iv) middle flow distributor 16 b. In this embodiment, layers (i)-(iv) may be located in the full diameter bed region, with no layers located in the reduced diameter bed region. Alternatively, the division between full diameter and reduced diameter may occur between layers (iii) and (iv). Additional layers may be added.

According to the alternative exemplary embodiments of FIGS. 8A and 8B, it will be appreciated that microcolumns 12 are shown having a first or upper extraction system or layered construction located in the upper full diameter bed region but no extraction system or layers in the lower reduced diameter bed region in which solid phase extraction or the like would have been conducted as in other embodiments herein. Such a reduced extraction system would have other clinical uses in single or dual stage applications, such as described below in connection with FIG. 10.

In a still further embodiment as shown in FIG. 9A, the extraction system is comprised of a four-layer sandwich construction, that includes: (i) middle compression layer 18 c in the reduced diameter region 31, (ii) extraction layer 14 of microparticulate extraction medium, (iii) lower compression layer 18 b, and optionally (iv) lower flow distributor/support 16 c which may be molded as part of the container. In this embodiment, layers (i)-(iv) may be located in the reduced diameter bed region, with no layers located in the full diameter bed region. Additional layers may be added.

And in a still further embodiment as shown in FIG. 9B, the extraction system is comprised of a four-layer sandwich construction, that includes: (i) middle compression layer 18 c in the reduced diameter region 31, (ii) air gap layer 314 in the place of extraction layer 14 (FIG. 9A), (iii) lower compression layer 18 b, and optionally (iv) lower flow distributor/support 16 c which may be molded as part of the container. In this embodiment, layers (i)-(iv) may again be located in the reduced diameter bed region, with no layers located in the full diameter bed region. Additional layers may be added.

According to the alternative exemplary embodiments of FIGS. 9A and 9B, it will be appreciated that microcolumns 12 are shown having a second or lower extraction system or layered construction located in the lower reduced diameter bed region but no extraction system or layers in the upper full diameter bed region in which the upper or middle flow distributor layers 16 a, 16 b or the like would have been positioned as in other embodiments herein. Such a reduced extraction system would have other clinical uses in single or dual stage applications, such as described below in connection with FIGS. 10 and 11.

All of the components of apparatus 10 are made of materials that are substantially inert to biological fluids so that when a biological fluid such as blood or urine is passed through apparatus 10, substantially nothing passes from apparatus 10 into the blood or urine. In one embodiment, microcolumn 12 is made of a biologically inert material. In one aspect, the biologically inert material is a plastic. In aspects of this embodiment, the biologically inert material is a fluorinated polymer or polypropylene. In other aspects the material is Polyphenelyne Sulfide (PPS), Polytetrafluoroethylene (PTFE), Polyether ether Ketone (PEEK), Polyoxymethylene (POM), Ethylene Propylene Diene (EPDM), a Fluorinated elastomer (FKM), a Perfluoro elastomer (FFKM), polysulfone (PSU), Ethylene Tetrafluoroethylene (ETFE), Polypropylene (PP), (Poly)Chlorotrifluoroethylene (PCTFE/CTFE), polystyrene, high density polyethylene, polycarbonate, nylon, or polyethylene terephthalate (PET), silicon, rubber, polyester, or ceramics.

A typical microcolumn according to the present invention has an internal diameter of about 0.01 inch to about 2 inches, about 0.025 inches to about 1.75 inches, about 0.05 inches to about 1.5 inches, of about 0.075 inches to about 1.25 inches, of about 0.1 inches to about 1 inch. In other aspects of this embodiment, the internal diameter is at least 0.01 inch, at least 0.025 inches, at least 0.05 inches, 0.075 inches, at least 0.1 inch, at least 0.25 inches, at least 0.5 inches, at least 0.75 inches, at least 1 inch, at least 1.25 inches, at least 1.5 inches, at least 1.75 inches, or at least 2 inches. In still other aspects of this embodiment, the internal diameter is at most 0.01 inch, at most 0.025 inches, at most 0.05 inches, 0.075 inches, at most 0.1 inch, at most 0.25 inches, at most 0.5 inches, at most 0.75 inches, at most 1 inch, at most 1.25 inches, at most 1.5 inches, at most 1.75 inches, or at most 2 inches. In a preferred embodiment the microcolumn has an internal diameter of about 0.1 inch to 1.0 inch.

A typical microcolumn according to the present invention has a length, excluding the tip if present, of about 0.25 inches to about 5 inches, 0.5 inches to about 4.5 inches, 0.5 inches to about 4 inches, 0.5 inches to about 3.5 inches, about 0.5 inches to about 3 inches, about 0.5 inches to about 2.5 inches, about 0.5 inches to about 2 inches, about 0.5 inches to about 1.5 inches, about 0.5 inches to about 1 inch, about 1.75 inches to about 3 inches, about 2 inches to about 3 inches, about 2.5 inches to about 3 inches. In other aspects of the invention, the microcolumn has a length of at least 0.25 inches, at least 0.5 inches, at least 0.75 inches, at least 1 inch, at least 1.25 inches, at least 1.5 inches, at least 2 inches, at least 2.25 inches, at least 2.5 inches, at least 2.75 inches, at least 3 inches, at least 3.25 inches, at least 3.5 inches, at least 3.75 inches, at least 4 inches, at least 4.25 inches, at least 4.5 inches, at least 4.75 inches, or at least 5 inches. In still further aspects, the microcolumn has a length, excluding the tip if present of at most 0.25 inches, at most 0.5 inches, at most 0.75 inches, at most 1 inch, at most 1.25 inches, at most 1.5 inches, at most 2 inches, at most 2.25 inches, at most 2.5 inches, at most 2.75 inches, at most 3 inches, at most 3.25 inches, at most 3.5 inches, at most 3.75 inches, at most 4 inches, at most 4.25 inches, at most 4.5 inches, at most 4.75 inches, or at most 5 inches. In a preferred embodiment, the microcolumn has a length, excluding the tip of about 0.5 inches to about 3 inches. The length of the tip (if present) is not particularly limited but may range from about 0.1 inch to 1 inch.

The upper full diameter bed region generally includes at least about 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or 85% of the total microcolumn length. In one embodiment, the upper full diameter bed region includes at least about 75% of the total microcolumn length.

The microcolumn of the apparatus need not have the shape shown in the figures. For example, it need not be cylindrical, and may instead have a square footprint, a polygonal footprint (e.g., hexagonal, octagonal, etc.), tubular, or include combinations of multiple shapes. As used herein “footprint” describes the shape of a horizontal cross-section of the interior cavity (i.e., passage 23) of the microcolumn. In one embodiment, the full diameter bed region has a first footprint shape, and the reduced diameter bed region has a second footprint shape, and the tip (if present) may have a third footprint shape (or may have the same footprint shape as either the full diameter bed region or the reduced diameter bed region).

In addition, in one embodiment of the invention, entrance 20 can be designed or configured to receive a connective fitting to connect the microcolumn to a fluid input device. Such connective fittings include luer tips, luer-lock extensions or tapers of various types, male and female-type connections of various types, threaded connections, or barb connections.

As used herein, a “fluid input device” is any device which is in contact with the entrance and directly transfers the sample or reagent to entrance 20 in a connected manner. Fluid input devices may include automated fluid dispensing systems, automated liquid handling platforms, syringes, and microdispensers. The fluid input device may dispense the sample or reagent to the microcolumn automatically, semi-automatically, or manually. For instance a fluid input device may include a reservoir containing a liquid sample, which once connected to the entrance, can automatically dispense sample to the microcolumn.

The narrow bore sandwich layer in the reduced diameter region can be assembled as a stand-alone column barrel design or patterned in a one-piece block format for automated processing.

The present apparatus may be in a single column format, which is convenient and cost effective for preparing a small number of samples, or a multi-column array or format (aka, an “extraction plate”), which is suited for preparing large numbers of samples in parallel.

One embodiment of the invention is an extraction plate configured for or containing the narrow bore columns discussed above. This extraction plate may be a molded plate containing a plurality of columns. The columns may be arrayed to align or intercalate with the wells of conventional “multi-well” formats, such that each column would elute into a well in a standard (or custom) multi-well plate. Multi-well formats are commonly used with robotic fluid dispensing systems, such as autosamplers. Typical multi-well formats are not limited, but include 48-, 96-, and 384- and 1,584-well standard plate formats.

Fluids are usually forced through the present apparatus and into the collection containers (or the wells of a “collection tray” or “plate”), either by drawing a vacuum across the device with a specially designed vacuum manifold, or by using centrifugal or gravitational force. In specially designed vacuum manifold systems, both the column and the receiving means (such as a well or collection tube) may be integrated into the vacuum system to optimize extraction. Centrifugal force is generated by placing the apparatus, together with a suitable collection tube or tray, into a centrifuge specifically designed for the intended purpose. However, in one embodiment gravity may be sufficient to force the fluid through the present apparatus as well.

The present apparatus may use conventional collection containers or collection plates, such as glass tubes, centrifuge tubes, Eppendorf tubes, or standard multi-well plates or trays. The present apparatus may alternately use collection containers specifically designed to be compatible with the present extraction plate.

Methods of using the present invention include extraction of an analyte from a test sample. A test sample refers to any sample that may contain an analyte of interest. A test sample may be a biological sample, that is, a sample obtained from any biological source, such as an animal, a plant, a fungus, a microorganism, a cell culture, an organ culture, etc. In aspects of this embodiment, a biological sample includes a blood sample including a whole blood sample, a plasma sample, or a serum sample, a saliva sample, a urine sample, cerebrospinal fluid sample, a bile sample, a tissue sample, or any other sample that can be obtained, extracted or isolated from a biological source. Such biological samples may be obtained, for example, from a patient; that is, a living person, male or female, presenting oneself in a clinical setting for diagnosis, prognosis, or treatment of a disease or condition. In one embodiment, the sample is obtained from a patient, for example, a plasma specimen. The plasma specimen may be taken with or without the use of anticoagulants.

A test sample may be an environmental sample. Environmental samples are samples taken from dirt, plant matter, or fluid sources (such as ground water, oceans, or rivers etc.). Dirt (aka “soil samples”) may be taken from agricultural sites or sites of environmental interest and may have the analyte extracted, including the removal of particulate matter.

The methods of using the present apparatuses include contacting the apparatus with the sample in a liquid buffer, and eluting the sample from the apparatus with an elution buffer. Further steps might include conditioning the apparatus and washing steps (before, during, or after contacting the apparatus with a sample).

The present apparatus may also be included in a kit specifically designed to capture and separate a particular analyte of interest. The microparticulate extraction media may be specifically adapted to separate specific analytes of interest. The kit may include suitable reagents (labels, washes, etc.), buffers or elution buffers, in concentrated form or in a form suitable for direct use. The kit may also include an extraction plate or array of columns as described above, and accompanying couplings to connect the plate to fluid dispensing devices and/or plates or vials for receiving the eluted solution containing the sample.

Turning next to FIGS. 10A-10C there is shown a further exemplary embodiment of an apparatus 110 for extracting an analyte from a liquid sample, here the apparatus 110 configured as a multi-column array or format (aka, an “extraction plate”) of microcolumns 112, 212 in series as by stacking or nesting one array of microcolumns on or over another, which arrangement is suited for preparing large numbers of samples in parallel and further for multi-stage extraction or elution as described further below. Here, there are thus formed an upper first array 170 of first microcolumns 112 and a lower second array 270 of second microcolumns 212. In the illustrated embodiment, each array 170, 270 comprises a plurality of microcolumns 112, 212 maintained in a substantially parallel and offset pattern or arrangement as by a respective top plate 160, 260 and base 162, 262—as illustrated, there are ninety-six (96) such microcolumns 112, 212 per array 170, 270, though it will be appreciated that such is merely exemplary. The nesting of respective first and second microcolumns 112, 212 may be achieved employing any appropriate technique now known or later developed. However, while a tight or interference fit or substantially sealed arrangement as typically configured may be employed in nesting the first and second microcolumns 112, 212 in series where the sample is drawn through both microcolumns 112, 212 simultaneously as by applying pressure or a vacuum or by centrifugal or gravitational force, uniquely according to aspects of the present invention a loose or unsealed nesting of the first and second microcolumns 112, 212 is to be employed so as to allow pressurizing the upper or first microcolumns 112 from the top without yet passing the liquid through to the lower or second microcolumns 212, more about which is said below. Notably, the configuration of the exit 22 or tip region 33 and/or the reduced diameter bed region 31 (FIG. 1A) of the first microcolumn 112 is such that there is a loose fit or gaps left when nesting in the entrance 20 at the full diameter bed region 30 of the second microcolumn 212 so as to allow venting and thus pressurization from above and activation of the first microcolumn 112 without necessarily activating, pressurizing, or flowing through the second microcolumn 212.

Referring to FIG. 10B, there is shown an enlarged partial cross-sectional view of an upper or first microcolumn 112 associated with the upper or first stage or array 170 of the apparatus 110, as taken along section line 10B-10B of FIG. 10A. Similar to the exemplary embodiments of FIGS. 8A and 8B, the first microcolumn 112 is shown as having a first or upper extraction system or layered construction located in the upper full diameter bed region 130 but no extraction system or layers in the lower reduced diameter bed region 131. Specifically, the upper first layered construction is comprised of: (i) upper flow distributor 116 a configured as a screen or mesh, (ii) upper compression layer 118 a such as a glass fiber filter material, (iii) optional sorbent or extraction layer 119, and (iv) optional frit 117. Again, additional layers may be added or substituted, it being noted, for example, the alternative position of the optional frit 117 at the bottom of the layers rather than at an intermediate position and of an upper sorbent 119 rather than a second flow distributor layer (compare to middle flow distributor 16 b of FIGS. 1B, 3, 7A, 7B, 8A and 8B).

And in FIG. 10C there is shown an enlarged partial cross-sectional view of a lower or second microcolumn 212 associated with the lower or second stage or array 270 of the apparatus 110 shown in FIG. 10A, as taken along section line 10C-10C of FIG. 10A. Similar to the exemplary embodiments of FIGS. 9A and 9B, the second microcolumn 212 is shown as having a second or lower extraction system or layered construction located in the lower reduced diameter bed region 231 but no extraction system or layers in the upper full diameter bed region 230. Specifically, the lower second layered construction is comprised of: (i) middle compression layer 218 c, (ii) extraction layer 214 of microparticulate extraction medium, and (iii) lower compression layer 218 b. Again, additional layers may be added or substituted, here it being noted, for example, that the lower and middle compression layers 218 b, 218 c may be frits or any other such materials bounding the extraction layer 214 and that the optional lower flow distributor/support 16 c (FIGS. 9A and 9B) which may be molded as part of the container is not included in the alternative exemplary lower or second microcolumn 212 associated with the second stage or array 270 of the apparatus 10. As also shown in FIG. 10C, optionally, microcolumn passage 223 may be tapered from the upper full diameter bed region 230 to the reduced diameter bed region 231, which it will be appreciated assists in transitioning the sample or elution liquid from one bed region to the other.

More generally, with continued reference to FIGS. 10A-10C, it will be appreciated that by configuring the apparatus 110 in two stages with two separate microcolumns 112, 212 in series, the upper first microcolumn 112 being configured with a layered construction in its upper full diameter bed region 130 and the lower second microcolumn 212 being configured with a layered construction in its lower reduced diameter bed region 231, there is achieved a multi-stage extraction system somewhat analogous to doing so in a single microcolumn 12 having two distinct bed regions and related layered constructions, or effectively two stages, but by doing so in two microcolumns 112, 212 in series more flexibility in use is beneficially derived. For example, by physically separating the upper and lower extraction or filtration systems between the two microcolumns 112, 212, larger volumes or spaces therebetween are formed, though with less dead spaces, both to serve as functional reservoirs for samples or elution liquids and effectively forming air gaps to prevent or mitigate against dripping or capillary flow and to allow for the transfer of the one or more columns between each other or to an appropriate receiving vessel or plate. In that regard, there is thus provided new functional utility and increased fields of use. In one embodiment, such a single-or multi-stage microcolumn alone or in an array functions as a test tube or incubation device, wherein a self-contained system is provided in which aqueous solutions will not readily leak out based on supported surface tension and other such factors yet with the ability to also serve as an effective sold phase extraction device. Furthermore, in the particular exemplary embodiment wherein the upper or first microcolumn 112 associated with the first stage comprises the optional sorbent or extraction layer 119, it will be appreciated that there is thus provided a true dual- or two-stage solid phase extraction apparatus 110. Those skilled in the art will appreciate that a variety of other arrangements of the microcolumns 112, 212 and the layered constructions within each are possible without departing from the spirit and scope of the invention. By way of further illustration and not limitation, when the first and second microcolumns 112, 212 are configured as set forth herein so as to nest in an unsealed or vented fashion, it will be appreciated that when a sample is first filtered or extracted in the upper or first stage microcolumns 112 pressure is applied thereto from above so as to in this example push the sample through the first or upper extraction system or layered construction located in the upper full diameter bed region 130 of each and have the sample flow downwardly and collect within the passage 223 of the respective lower or second microcolumns 212 above the second or lower extraction system or layered construction located in the lower reduced diameter bed region 231 of each lower second microcolumn 212 without flowing or being forced therethrough, again because the pressure applied to the upper first microcolumns 112 is vented. Once the sample is prepared as through filtration or extraction via the first microcolumns 112, the upper or first array 170 of microcolumns 112 may simply be removed or jettisoned and then further processing conducted on the lower or second array 270 of microcolumns 212, as by then pressurizing the second microcolumns 212 and/or employing an elution solvent to release the analytes of interest. It will be appreciated that a variety of mechanisms for manually, semi-automatically or automatically selectively activating or filtering with the upper first array 170 of microcolumns 112 and then the lower second array 270 of microcolumns 212, whether now known or later developed, are possible according to aspects of the present invention, which will be further appreciated by the further discussion and examples herein. It will also be appreciated that while the second stage filtration or extraction activation may be accomplished using pressure, centrifuge or gravity or other such techniques now known or later developed to draw the sample through the second microcolumns 212 may also be employed without departing from the spirit and scope of the present invention.

Referring next to FIGS. 11A-11C there is shown a still further exemplary embodiment of an apparatus 110 for extracting an analyte from a liquid sample similar to that of FIGS. 10A-10C with the apparatus 110 again configured as a multi-column array or format (aka, an “extraction plate”) of microcolumns 112, 212 in series as by stacking or nesting one array of microcolumns on or over another. Once more, there are thus formed an upper first array 170 of first microcolumns 112 and a lower second array 270 of second microcolumns 212. In the illustrated embodiment, each array 170, 270 comprises a plurality of microcolumns 112, 212 maintained in a substantially parallel and offset pattern or arrangement as by a respective top plate 160, 260 and base 162, 262—as again illustrated, there are ninety-six (96) such microcolumns 112, 212 per array 170, 270, though it will be appreciated that such is merely exemplary. The nesting of respective first and second microcolumns 112, 212 may again be achieved employing any appropriate technique now known or later developed, including sealed (tight) and unsealed (loose) fit arrangements, though there again being advantages in the present multi-stage arrangement and micro elution bed configuration to loosely nesting the respective microcolumns 112, 212 so as to vent therebetween.

As shown in the enlarged partial cross-sectional view of an upper or first microcolumn 112 associated with the upper or first stage or array 170 of the apparatus 110 of FIG. 11B, here as taken along section line 11B-11B of FIG. 11A, similar to the exemplary embodiments of FIGS. 8A and 8B and FIG. 10B, the first microcolumn 112 is shown as having a first or upper extraction system or layered construction located in the upper full diameter bed region 130 comprised of: (i) upper flow distributor 116 a configured as a screen or mesh, (ii) upper compression layer 118 a such as a glass fiber filter material, (iii) optional sorbent or extraction layer 119, and (iv) optional frit 117. Furthermore, the upper or first microcolumn 112 also includes an additional extraction system or layered construction in the lower reduced diameter bed region 131, here shown much like that of the embodiment of FIG. 7B wherein there is provided: (i) middle compression layer 118 c, (ii) air gap layer 114 (rather than an extraction layer 14 as in FIGS. 1B and 3), and (iii) lower compression layer 118 b. It will be appreciated that the space between the upper extraction system or layered construction, here including an optional lowest layer as frit 117, and the top of the lower extraction system or layered construction, here being the middle compression layer 118 c, defines yet another air gap layer analogous to the air gap layer 301 of FIG. 7B. Thus, there are effectively two air gap layers in the upper or first microcolumn 112 alone in this alternative exemplary embodiment. Once again, those skilled in the art will appreciate that the number, arrangement, and actual or proportional size of any such air gaps are merely illustrative of aspects of the present invention and non-limiting. It is again noted in connection with FIG. 11B that, though not shown, an optional lower flow distributor/support analogous to such distributor 16 c shown in FIG. 7B may be molded as part of the container or otherwise provided as part of the lower reduced diameter bed region 131 of the upper or first microcolumn 112. Again, additional layers may be added or substituted, it being noted, for example, the alternative position of the optional frit 117 and the inclusion of an upper sorbent 119 rather than a second flow distributor layer (compare to middle flow distributor 16 b of FIGS. 1B, 3, 7A, 7B, 8A and 8B).

And in FIG. 11C there is again shown an enlarged partial cross-sectional view of a lower or second microcolumn 212 associated with the lower or second stage or array 270 of the apparatus 110 shown in FIG. 11A, as taken along section line 11C-11C of FIG. 11A. For simplicity, the second microcolumn 212 of FIG. 11C is shown as being identical to that of FIG. 10C, though it will be appreciated that other such configurations of the lower or second extraction system or layered construction located in the lower reduced diameter bed region 231, with or without an extraction system or layers in the upper full diameter bed region 230, may be employed without departing from the spirit and scope of the invention. In the illustrated embodiment, once again, the lower second layered construction is comprised of: (i) middle compression layer 218 c, (ii) extraction layer 214 of microparticulate extraction medium, and (iii) lower compression layer 218 b, with additional layers being added or substituted depending on the context. As also again shown in FIG. 11C, optionally, microcolumn passage 223 may be tapered from the upper full diameter bed region 230 to the reduced diameter bed region 231 to assist in transitioning the sample or elution liquid from one bed region to the other.

Regarding the alternative embodiment of the apparatus 110 as shown in FIGS. 11A-11C, it will again be appreciated that there are provided two stages with two separate microcolumns 112, 212 in series, the upper first microcolumn 112 being configured with a layered construction at least in its upper full diameter bed region 130 and the lower second microcolumn 212 being configured with a layered construction in its lower reduced diameter bed region 231. Accordingly, there is once more achieved a multi-stage extraction system as generally shown and described herein with at least two distinct bed regions and related layered constructions, or effectively two stages, again doing so in two microcolumns 112, 212 in series. As noted above in connection with the alternative upper or first microcolumn 112 of the present embodiment, by including spaced apart middle and lower compression layers 118 c, 118 b there are provided two air gaps in the first microcolumn 112 alone, and again, by physically separating the upper and lower extraction or filtration systems between the two microcolumns 112, 212, larger volumes or spaces therebetween are formed that further serve as air gaps, all such air gaps cooperating to prevent or mitigate against dripping or capillary flow and to allow for the transfer of the one or more columns between each other or to an appropriate receiving vessel or plate. Moreover, in the exemplary arrangement of the upper or first microcolumn 112 as shown in FIG. 11B, a further alternative embodiment might be to include an extraction layer or sorbent analogous to extraction layer 14 in FIGS. 1B, 3 and 9A rather than the air gap 114 shown in FIG. 11B. It will be appreciated that the result in this alternative exemplary embodiment would be effectively three extraction systems or a three-stage solid-phase extraction system achieved using two of the novel microcolumns 112, 212 in series according to aspects of the present invention, with two such stages occurring in the upper first microcolumn 112 and an effective third stage in the lower second microcolumn 212. It will be further appreciated that a four-stage arrangement could be provided by also including an extraction system in the upper full diameter bed region 230 of the lower or second microcolumn 212, or there may be only one stage in the upper first microcolumn 112 as shown in FIGS. 10B and 11B and instead two stages in the lower second microcolumn 212. Again, those skilled in the art will appreciate that any such arrangements or configurations are possible without departing from the spirit and scope of the invention, including having two or more stages and two or more microcolumns in series, with the stages distributed among the microcolumns in a wide variety of arrangements. In that regard, there is once more thus provided new functional utility and increased fields of use in the extraction apparatus 110 according to aspects of the present invention, whereby relatively more effective extraction as measured by absolute recovery or otherwise is possible even using the same or smaller elution volume, resulting in less dead or unused volume and less contaminates in the extracted analytes.

Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. For example, the apparatus 10 is not limited to use with biological fluids, but can be used, for example, for testing ground water, drinking water, and other liquids for contaminants.

Aspects of the present specification may also be described as follows:

1. An apparatus for extracting an analyte from a liquid sample comprising: a) a container having an entrance, an exit, and a passage therebetween for passage of a liquid sample containing an analyte therethrough, said container having a full diameter bed region and a reduced diameter bed region; b) within the passage in the reduced diameter bed region, a thin layer of microparticulate extraction media, wherein the extraction media layer has a top surface, a bottom surface, and a peripheral edge, and the extraction media layer is oriented in the passage so that liquid flows through the extraction media layer from its top surface to the bottom surface; c) an upper compression layer in the full diameter bed region having an effective diameter bed area, located at or spaced above the top surface of the extraction media layer and a lower compression layer in the reduced diameter bed region, located at or spaced below the bottom surface of the extraction media layer, the two compression layers pressing the extraction media therebetween, wherein the effective area of the of the extraction media is smaller than the effective area of the upper compression layer; and d) an upper mesh flow distributor above the upper compression layer for distributing flow of the liquid sample uniformly to the extraction media layer top surface.

2. The apparatus of embodiment 1, wherein the ratio between the effective area of the extraction media to the effective area of the upper compression layer is about 1:10.

3. The apparatus of embodiment 1 or embodiment 2, wherein the ratio between the effective area of the extraction media to the effective area of the upper compression layer is about 1:4.

4. The apparatus of any one of embodiments 1-3, wherein the extraction media has a number average particle size of about less than 20 μm.

5. The apparatus of any one of embodiments 1-4, wherein the extraction media has a small particle size having a number average particle size of less than about 40 microns, less than about 30 microns, less than about 25 microns, less than about 20 microns, less than about 15 microns, less than about 10 microns, or less than about 5 microns.

6. The apparatus of any of embodiments 1-5, wherein the extraction media comprises particles that are sorbent particles selected from ion exchange sorbents, reversed phase sorbents, and normal phase sorbents.

7. The apparatus of embodiment 6, wherein the sorbent particles are selected from an inorganic material such as SiO₂ or an organic polymeric material such as poly(divinylbenzene), silica based particles (such as silica based carboxylic acids), diatomaceous earth particles, polymeric based particles, mono-dispersed silica and polymeric particles, and/or carbon graphite particles.

8. The apparatus of embodiment 7, wherein the sorbent particles are treated with an organic functional group such as a C₂-C₂₂, preferably C₈-C₁₈, functional group.

9. The apparatus of any of embodiments 1-8, wherein the extraction bed comprises at least two different extraction media in a single bed.

10. The apparatus of any of embodiments 1-9, wherein the apparatus further comprises one or more additional extraction beds.

11. The apparatus of any of embodiments 1-10, wherein the extraction media is loosely packed or is compacted.

12. The apparatus of any of embodiments 1-11, wherein one or more of the compression layers is flat, spherical, a truncated cone, prismatic, or a truncated pyramid.

13. The apparatus of any of embodiments 1-12, wherein one or more of the compression layers has a pore size less than the particle size of the extraction media.

14. The apparatus of embodiment 13, wherein one or more of the compression layers has a pore size of less than 5 microns or less than 3 microns.

15. The apparatus of any of embodiments 1-14, wherein the compression layers are composed of a flexible, hydrophobic material.

16. The apparatus of embodiment 15, wherein the compression layer comprises a glass microfiber media and/or a polymer.

17. The apparatus of embodiment 15, wherein the compression layer comprises polypropylene or polyethylene.

18. The apparatus of any of embodiments 1-17, wherein the compression layer has a thickness ranging from about 0.1 mm to about 3.25 mm, about 0.25 mm to about 3.25 mm, about 0.5 mm to about 3.0 mm, about 0. 75 mm to about 3 mm, about 0.25 mm to about 2.5 mm, about 0.25 mm to about 2 mm, about 0.25 mm to about 1.5 mm, about 0.25 mm to about 1.25 mm, about 0.25 mm to about 1.0 mm, about 0.1 mm to about 0. 75 mm, or about 0.1 mm to about 0.5 mm.

19. The apparatus of any of embodiments 1-18, wherein the flow distributor is a flexible mesh material having a mesh number of 200 or higher.

20. The apparatus of any of embodiments 1-19, wherein the flow distributor comprises one or more of Polyphenelyne Sulfide (PPS), Polytetrafluoroethylene (PTFE), Polyether ether Ketone (PEEK), Polyoxymethylene (POM), Ethylene Propylene Diene (EPDM), a Fluorinated elastomer (FKM), a Perfluoro elastomer (FFKM), polysulfone (PSU), Ethylene Tetrafluoroethylene (ETFE), Polypropylene (PP), (Poly)Chlorotrifluoroethylene (PCTFE/CTFE), polystyrene, high density polyethylene, polycarbonate, nylon, polyethylene terephthalate (PET), silicon, rubber, or polyester.

21. The apparatus according to any of embodiments 1-20, further comprising a middle flow distributor below the upper compression layer and/or a lower flow distributor below the lower compression layer.

22. The apparatus according to embodiment 21, wherein the flow distributors are layered or molded in the housing above and below the compression layers.

23. The apparatus according to embodiment 22, wherein the upper flow distributor is located in the full diameter region and the lower flow distributor is seated in a lower portion of the apparatus, having a reduced diameter.

24. The apparatus according to any of embodiments 1-23, wherein the apparatus is configured for an elution volume of about 0.025 ml to about 0.25 ml, about 0.025 ml to about 0.2 ml, about 0.025 ml to about 0.15 ml, about 0.025 ml to about 0.100 ml.

25. The apparatus according to any of embodiments 1-24, wherein the entrance is configured to receive a connective fitting to connect the apparatus to a fluid input device.

26. The apparatus according to any of embodiments 1-25, wherein the fluid input device comprises automated fluid dispensing systems, automated liquid handling platforms, syringes, and microdispensers

27. An extraction plate comprising multiple apparatuses according to any of embodiments 1-26.

28. The extraction plate according to embodiment 27, wherein the apparatuses are arranged in a multicolumn array.

29. An apparatus for extracting an analyte from a liquid sample comprising: a) a container having an entrance, an exit, and a passage therebetween for passage of a liquid sample containing an analyte therethrough, said container having a full diameter bed region and a reduced diameter bed region; and b) a layered construction having a top and a bottom extending across the passage, comprising from top to bottom: (i) an upper flow distributor/support layer, (ii) an upper compression layer, (iii) an extraction layer of microparticulate extraction medium adjacent to the layer (ii), and (iv) a lower compression layer located adjacent to the extraction layer (iii), wherein the (i) upper flow distributer and (ii) upper compression layer are located in the full diameter region, the (iii) extraction layer and (iv) lower compression layer are located in the reduced diameter region.

30. The apparatus of embodiment 29, wherein the full diameter region has an effective bed area measured by A_(F)=πr_(F) ², where r_(F) is the radius of an interior surface of the container in the full diameter region, and A_(r)=πr_(r) ^(2 where r) _(r) is the radius of an interior surface of the container in the reduced diameter region, and wherein the ratio between the effective bed area of the full diameter region and the effective area of the reduced diameter region ranges from about 10:1 to 1.5:1.

31. The apparatus of embodiment 29, wherein the ratio between the effective bed area of the full diameter region and the effective area of the reduced diameter region is about 4:1.

32. The apparatus of embodiment 29, wherein the layered construction having a top and a bottom extending across the passage, comprises from top to bottom: (i) an upper flow distributor, (ii) an upper compression layer, (i′) a middle flow distributor, (ii′) a middle compression layer in the reduced diameter region, (iii) an extraction layer of microparticulate extraction medium adjacent to the layer (ii′), (iv) a lower compression layer adjacent to layer (iii), and (v) optionally, a lower flow distributor, wherein layers (i), (ii), (i′), and (ii′) are located in the full diameter region, and layers (iii)-(v) may be located in the reduced diameter region.

33. The apparatus of embodiment 29, wherein the layered construction having a top and a bottom extending across the passage, comprises from top to bottom: (i) an upper flow distributor, (ii) an upper compression layer, (i′) a middle flow distributor, (ii′) a middle compression layer in the reduced diameter region, (iii) an extraction layer of microparticulate extraction medium adjacent to the layer (ii′), (iv) a lower compression layer adjacent to layer (iii), and (v) optionally, a lower flow distributor, wherein layers (i), (ii), and (i′), are located in the full diameter region, and layers (ii′)-(v) are located in the reduced diameter region

34. The apparatus of embodiment 29, further comprising one or more air gap layer(s).

35. The apparatus of embodiment 34, wherein an air gap layer is located in the reduced-diameter region.

36. The apparatus of embodiment 35, wherein the air gap layer has a height that ranges from ½ the diameter of the reduced diameter region to 4 times the diameter of the reduced diameter region.

37. The apparatus of embodiment 33, further comprising an air gap layer located between layer (i′) and layer (ii′).

38. The apparatus of embodiment 37, wherein the air gap layer is located in the reduced diameter region.

39. The apparatus according to any of embodiments 34-38, wherein the air gap has a height range from about 0.5 to about 1 times, about 0.5 to about 1.5 times, about 0.5 to about 2 times, about % to about 2.5 times, about 0.5 to about 3 times, about 0.5 to about 3.5 times, about % to about 4 times, about 1 to about 1.5 times, about 1 to about 2 times, about 1 to about 2.5 times, about 1 to about 3 times, about 1 to about 3.5 times, about 1 to about 4 times, about 1.5 to about 2 times, about 1.5 to about 2.5 times, about 1.5 to about 3 times, about 1.5 to about 3.5 times, about 1.5 to about 4 times, about 2 to about 2.5 times, about 2 to about 3 times, about 2 to about 3.5 times, about 2 to about 4 times, about 2.5 to about 3 times, about 2.5 to about 3.5 times, about 2.5 to about 4 times, about 3 to about 3.5 times, about 3 to about 4 times, or about 3.5 to about 4 times, the diameter of the reduced diameter region.

40. The apparatus of any of embodiments 1-26 or embodiments 29-39, further comprising a tip region

41. The apparatus according to embodiment 40, wherein the tip region is cylindrical or conical.

42. The apparatus according to embodiment 41, where in the tip region has the same diameter of the reduced diameter bed region or a smaller diameter bed than the reduced diameter bed region.

43. The apparatus according to any of embodiments 40-42, wherein the tip region is in the form of a luer tip.

44. An apparatus for extracting an analyte from a liquid sample comprising: a) a microcolumn having an entrance, an exit, and a passage therebetween for passage of a liquid sample containing an analyte therethrough, the microcolumn having a full diameter bed region and a reduced diameter bed region; and b) an extraction system having a top and a bottom extending across the passage, the extraction system comprising at least one of: a first layered construction comprising from top to bottom: (i) an upper flow distributor layer and (ii) an upper compression layer, the first layered construction located in the full diameter bed region; and a second layered construction comprising from top to bottom: (iii) a middle compression layer and (iv) a lower compression layer, the second layered construction located in the reduced diameter bed region.

45. The apparatus of embodiment 44 wherein the extraction system comprises only the first layered construction.

46. The apparatus of embodiment 44 or embodiment 45 wherein the first layered construction further comprises a middle flow distributor layer positioned beneath the upper compression layer.

47. The apparatus of embodiment 46 wherein the first layered construction further comprises a frit positioned between the middle flow distributor layer and the upper compression layer.

48. The apparatus of any of embodiments 44-47 wherein the first layered construction further comprises a frit positioned beneath the upper compression layer.

49. The apparatus of any of embodiments 44-48 wherein the first layered construction further comprises an extraction layer beneath the upper compression layer.

50. The apparatus of embodiment 44 wherein the extraction system comprises only the second layered construction.

51. The apparatus of any of embodiments 44-50 wherein the second layered construction further comprises an extraction layer of microparticulate extraction medium between the middle compression layer and the lower compression layer.

52. The apparatus of any of embodiments 44-51 wherein the second layered construction further comprises an air gap between the middle compression layer and the lower compression layer.

53. The apparatus of any of embodiments 44-52 wherein the second layered construction further comprises a lower flow distributor beneath the lower compression layer.

54. The apparatus of any of embodiments 44-53 wherein an air gap is formed between the upper compression layer of the first layered construction and the middle compression layer of the second layered construction.

55. The apparatus of embodiment 44 wherein the extraction system comprises at least one first layered construction and at least one second layered construction.

56. The apparatus of any of embodiments 44-55 further comprising multiple microcolumns in an array.

57. The apparatus of any of embodiments 44-56 further comprising multiple microcolumns in series so as to define at least a first microcolumn associated with a first stage and a second microcolumn associated with a second stage.

58. The apparatus of embodiment 57 wherein the first microcolumn engages the second microcolumn with unsealed nesting.

59. An apparatus for extracting an analyte from a liquid sample comprising: a) an upper first microcolumn and a lower second microcolumn selectively in series, each microcolumn having an entrance, an exit, and a passage therebetween for passage of a liquid sample containing an analyte therethrough, whereby the first microcolumn defines a first passage and the second microcolumn defines a second passage, each microcolumn further having a full diameter bed region and a reduced diameter bed region; b) a first layered construction having a top and a bottom extending across the first passage of the first microcolumn, comprising from top to bottom: (i) an upper flow distributor/support layer and (ii) an upper compression layer, the first layered construction located in the full diameter bed region of the first microcolumn; and c) a second layered construction having a top and a bottom extending across the second passage of the second microcolumn, comprising from top to bottom: (iii) an extraction layer of microparticulate extraction medium and (iv) a lower compression layer, the second layered construction located in the reduced diameter bed region of the second microcolumn.

60. The apparatus of embodiment 59 wherein the first layered construction further comprises an extraction layer beneath the upper compression layer.

61. The apparatus of embodiment 59 or embodiment 60 comprising a third layered construction having a top and a bottom extending across the first passage of the first microcolumn, comprising from top to bottom: (i) a middle compression layer and (ii) a lower compression layer, the third layered construction located in the reduced diameter bed region of the first microcolumn.

62. The apparatus of embodiment 61 wherein the third layered construction further comprises an air gap between the middle compression layer and the lower compression layer.

63. The apparatus of embodiment 61 or embodiment 62 wherein the third layered construction further comprises an extraction layer between the middle compression layer and the lower compression layer.

64. A method for the extraction of an analyte from a sample comprising: a) contacting an apparatus or extraction plate of any of embodiments 1-63 with a sample in a liquid buffer, and b) eluting the sample from the apparatus with an elution buffer.

65. The method according to embodiment 64, further comprising one or more conditioning or washing steps before, during, or after contacting the apparatus with the sample.

66. The method of embodiment 64 or embodiment 65 wherein the step of contacting the apparatus comprises filtering the sample through the first microcolumn under pressure and flowing the sample into the second microcolumn under reduced pressure as by unsealingly nesting the first microcolumn within the second microcolumn so as to provide ventilation.

67. The method of any of embodiments 64-66 wherein the step of contacting the apparatus further comprises removing the first microcolumn and filtering the sample through the second microcolumn and the step of eluting the sample from the apparatus comprises flowing the elution buffer through the second microcolumn

68. A kit comprising an apparatus or extraction plate according to any of embodiments 1-63.

69. The kit according to embodiment 68, further comprising one or more elution buffers or wash buffers.

EXAMPLES

The following non-limiting examples are provided for illustrative purposes only in order to facilitate a more complete understanding of the disclosed subject matter. These examples should not be construed to limit any of the embodiments described in the present specification, including those pertaining to the apparatus used therein and the methods of using the present apparatus.

Example 1 Extraction of the Catecholamines from Plasma

Control Single diameter column: CEREX® WCX 1 cc 10 mg columns.

Present Apparatus “narrow bore column”: The narrow bore column was a 1 cc column having an effective area ratio of 4:1 (full diameter to reduced diameter). The layers of the column were: (i) an upper flow distributor screen, (ii) a cylindrical fabric compression layer, (iii) a lower flow distributor screen, (iv) a spherical frit as a compression layer, (v) the microparticulate extraction medium, and (vi) a spherical frit as a lower compression layer. Layers (i)-(iii) were located in the full diameter region, where layers (iv)-(vi) were located in the reduced diameter region. The extraction medium was the same as the extraction medium used in the CEREX® WCX 1 cc 10 mg columns.

Normal human serum samples were obtained from Bioreclamation Corp. and spiked with catecholamines prior to solid phase extraction. The blanks and plasma samples were also spiked with internal standards (e.g., dopamine-D4, epinephrine-D6, and norepinephrine-D6).

CEREX® WCX (1 cc /10 mg) (control and narrow bore) columns were conditioned with 0.5 ml of methanol, followed by 0.5 ml of 10 mM Phosphate Buffer pH 6.8.

0.5 mL 10 mM Phosphate buffer was mixed with 100 μL of the Sample. The Sample/buffer mix at a pH of 6.8 was loaded onto the column at a pressure of 2-3 psi. The column was washed with 1 mL deionized water at 6 psi and subsequently washed with 1 ml Acetonitrile at 6 psi.

Two sets of columns were loaded for each type of column. One half of the columns (control and narrow bore) were eluted with 0.5 mL of Elution Buffer−25:75 100 mM Potassium Carbonate:Acetonitrile. The other half of the columns were eluted with 0.1 mL of 25:75 100 mM Potassium Carbonate:Acetonitrile.

25 μL of the eluent was used or loaded for the LC-MS/MS reaction.

Example 2 LC-MS/MS Analysis of the Catecholamines

25 μL of the solution obtained from the extraction was automatically injected into a TARGA® C18 3 μm particle size 50×2.1 mm analytical column. A binary HPLC gradient was applied to the analytical column to separate the epinephrine, norepinephrine and dopamine from other analytes contained in the sample. Mobile phase A was 5.0 mM ammonium formate with 0.1% formic acid pH 3.0 and mobile phase B was Acetonitrile with 0.1% formic acid. The HPLC gradient proceeded at a temperature of 35° C. with a flow rate of 500 μL/min over five minutes as follows:

Gradient: Time (min) B (%) 0.01 50 3.00 100 4.00 100 4.50 50 5.00 50

MS/MS was performed using an APPLIED BIOSYSTEMS MDS SCIEX 500®, although other suitable MS/MS apparatuses are known. The following software programs were used in the present examples: ANALYST 1.5.2®, although other suitable software systems are known. Liquid solvent/analyte exiting the analytical column flowed to the heated nebulizer interface of the MS/MS analyzer. The solvent/analyte mixture was converted to vapor in the heated tubing of the interface. Analytes in the nebulized solvent were ionized by heated ESI.

Ions passed to the first quadrupole (Q1), which selected ions with a mass to charge ratio of parent ions generated from one of the analytes. Ions entering quadrupole 2 (Q2) collided with argon gas to generate ion fragments, which were passed to quadrupole 3 (Q3) for further selection. After measurement of ions indicative of one of the analytes, Q1 was adjusted so that ions with a mass to charge ratio of parent ion from a second analyte were selected. These ions were collided with nitrogen gas in Q2, and the ion fragments passed to Q3 for further selection. After measurement of these ions, Q1 was adjusted so that ions with a mass to charge ratio of parent ion from a third analyte were selected. These ions were collided with argon gas in Q2, and the ion fragments passed to Q3 for further selection. Simultaneously, the same process using isotope dilution mass spectrometry was carried out with internal standards, dopamine-D4 and/or epinephrine-D6, and/or norepinephrine-D6. The following mass transitions were used for detection and quantitation of epinephrine, norepinephrine and dopamine (and their corresponding internal standards) during validation on positive polarity from the same sample injection.

Table 1 shows the data representing the percent recovery of catecholamines from a plasma sample spiked with 1 ng/ml catecholamine. Notably, the narrow bore columns performed significantly better for all catecholamines at all elution volumes. In particular, the small volume elution (i.e., the 0.1 ml elution) performed at least approximately three times as well as the small volume elution using the conventional column.

TABLE 1 Absolute Recovery Comparison at 1 ng/ml Plasma Cerex 10 mg 1 cc Cerex 10 mg 1 cc Cerex 10 mg 1 cc Cerex 10 mg 1 cc WCX column WCX column WCX Narrow Bore WCX Narrow Bore Compound 0.5 ml elution 0.1 ml elution 0.5 ml elution 0.1 ml elution Dopamine 98.3% cv = 8.3%  27.6% cv = 11.5% 99.5% cv = 4.6% 99.6% cv = 4.4% Dopamine-D4 96.8% cv = 9.8%  32.4% cv = 10.4% 99.5% cv = 4.2% 98.6% cv = 4.7% Epinephrine 92.3% cv = 12.6% 35.6% cv = 11.5% 97.5% cv = 3.8% 97.2% cv = 5.0% Epinephrine-D6 91.4% cv = 12.8% 38.5% cv = 13.2% 96.7% cv = 4.1% 98.1% cv = 4.5% Norepinephrine 87.3% cv = 14.3% 15.6% cv = 22.5% 93.0% cv = 5.8% 92.1% cv = 6.2% Norepinehrine-D6 85.6% cv = 15.2% 13.9% cv = 23.0% 91.5% cv = 5.4% 90.9% cv = 5.7%

As shown in the chromatograms of FIGS. 4A-F and FIGS. 5A-F, extracting and detecting catecholamine in plasma from healthy donors by using the present apparatus (i.e., the narrow bore column) is plotted over time.

The chromatography demonstrates the sensitivity of the assay. The absolute recovery chart demonstrates the improved recovery and improved reproducibility using the narrow bore columns vs conventional columns, even at smaller elution volumes.

Another benefit of the present apparatus is that due to the smaller elution volumes from the reduced effective bed diameter the present apparatus can collect into smaller vessels and eliminate or reduce transfers.

Example 3 Extraction of Buprenorphine and Norbuprenorphine from Urine

Narrow Bore Extraction columns feature high-capacity, high-efficiency, low bed mass sorbents that permit the use of low elution volumes (50-100 μL). These elution volumes lend themselves to evaporation within the positive pressure SPE processor unit such as an ALDIII™ or an IP8™ (SPEware Corp., Baldwin Park, Calif.), eliminating the need fora separate solvent evaporator. This allows the use of selective elution solvents, resulting in cleaner extracts than would be possible using high solvent strength (low specificity) elution solvents.

Buprenorphine and norbuprenorphine were chosen as model compounds for several reasons. They are frequently monitored as part of “pain panels” in compliance testing laboratories. Their relevant concentrations are relatively low and thus require low LLODs. Additionally, they are excreted in urine primarily as glucuronide conjugates, affording the opportunity to evaluate both solid phase extraction efficiency with narrow bore SPE columns.

Experimental Reagents

a) water, b) negative control urine (diluent for the standard curve), and c) a “master mix” containing 100 mM sodium acetate buffer pH 4.8, the internal standard solution (B-d4 and N-d3), and β-glucuronidase solution (2500 units/sample, catalog #BG100, red abalone, Kura Biotec, Inglewood, Calif.).

Process

A calibration curve was prepared from a single high calibrator via serial dilution. “Master mix” was placed in all wells of a 96-well incubation plate on the plate heater (preheated to 68° C.). Calibrators and controls (100 μL specimen volume) were then transferred to the incubator plate. After 15 minutes, the contents of the incubation plate were transferred to the 96-well SPE plate for extraction.

Solid Phase Extraction:

-   Apply samples to narrow bore extraction columns with PSCX sorbent     (2.5 mg) -   Wash w/250 μL deionized water -   Wash w/150 μL 100 mM acetic acid -   Wash w/300 μL methanol -   Dry sorbent for 1 minute -   Transfer the SPE plate to collection -   Elute w/50 μL elution solvent (ethyl acetate:methanol:conc.     NH4OH=93:5:2) -   Dry the solvent -   Dissolve residues in the reconstitution solvent (100 mL, aqueous     formic acid 0.1%:methanol=80:20)

Analytical Conditions

LC Conditions:

-   Column: Haisil C18 HL, 50×2.1 mm, 5 μM (Higgins Analytical, Inc.,     Mountain View, Calif.) -   Flow: 400 μL/min -   Injection volume: 10 μL -   A=0.1% Aqueous formic acid; B=Methanol; -   Gradient: 20-40% B in 0.5 min., 40-60% B in 2 min. -   MS Conditions: Sciex 5000, Source=ESI; Positive ion MRM -   Buprenorphine 468.25->55.10 (quant), 83.2 (qual) -   Buprenorphine-d4 472.42->59.0 (quant), 83.0 (qual) -   Norbuprenorphine 414.200->55.10 (quant), 83.0 (qual) -   Norbuprenorphine-d3 417.01->54.8 (quant), 83.1 (qual)

Results and Conclusions

Calibration curves for B and N are shown in FIGS. 6A-B. Regression is quadratic, 1/x weighted. Based on s/n ratios of the quantitation ions and assessment of curve accuracy (requiring ±20% from nominal value at the low calibrator), the LLOQs were determined to be 0.313 ng/mL and 0.625 for B and N, respectively.

Results from the analysis of non-validated control samples (n=10 each) are as follows:

TABLE 2 Burprenorphine Buprenorphine Hydrolysis Hydrolysis Low Control #1 Low Control #2 Control Low Control #1 Low Control #2 Control 0.75 ng/mL 1.2 ng/mL 5.0 ng/mL 100 ng/mL 150 ng/mL 100 ng/mL Average 0.91 1.4 5.3 107 167 110 Bias  22%  16%   6%   7%  11%  10% CV (RSD) 3.1% 3.1% 3.6% 3.2% 4.0% 3.6%

TABLE 3 Norbuprenorphine Norbuprenorphine Hydrolysis Hydrolysis Low Control #1 Low Control #2 Control Low Control #1 Low Control #2 Control 0.75 ng/mL 1.2 ng/mL 5.0 ng/mL 100 ng/mL 150 ng/mL 100 ng/mL Average 0.97 1.4 4.7 106 165 103 Bias  29%  16%  −6%   6%  10%   3% CV (RSD) 3.5% 4.0% 4.8% 2.7% 4.0% 5.6%

RSDs were less than 5%. Absolute recoveries from urine using the Narrow Bore Extraction column with a 2.5 mg bed mass were 91% and 97% for B and N, respectively. The experiment was repeated with a urine sample supplemented with morphine at 20,000 ng per mL. No difference in absolute recovery was noted.

Example 4 Extraction of Benzoylecgonine, Buprenorphine, EDDP, and Meprobamate from Urine

The following experiment compares extraction recovery of four (4) common analytes in urine with regular CEREX HPSCX NBE columns and a set of dual stage SPE columns with filtration only on the first stage and HPSCX sorbent in the narrow bore second stage without top filtration layers.

A blank urine sample was spiked with 100 ng of benzoylecgonine, buprenorphine, EDDP, and meprobamate with their deuterated internal standards.

Sample Preparation

Regular NBE Columns:

Urine sample (50 uL) was mixed with 100 mM sodium acetate (aq., pH 4.8, 250 uL) and loaded into the NBE SPE columns. Washing the columns with 100 mM HCl (300 uL), then DI water (500 uL), dry the columns with a stream of nitrogen for 10 minutes. Elute the sample with the elution buffer (DCM:IPA:NH4OH=80:18:2, 50 uL). The eluted samples were dried over nitrogen. The residue was reconstituted with 200 μL of a mixture of 0.1% aqueous formic acid:methanol=95:5 and spiked with IS. The samples were analyzed via LCMS.

Solid Phase Extraction with Dual Stage NBE Columns:

Urine samples (50 uL) was mixed with 100 mM sodium acetate (aq., pH 4.8, 250 uL) and loaded into the dual stage NBE columns. The samples were applied to the second stage columns through the first columns. The first stage columns were removed. The samples were loaded onto the sorbent in the second stage columns. The columns with sorbent were washed with 100 mM HCl (300 uL), then DI water (500 uL). Columns were dried through a stream of nitrogen for 10 minutes. The residue was reconstituted with 100 μL of a mixture of 0.1% aqueous formic acid:methanol=90:10 and skipped with IS. The samples were analyzed via LCMS.

Process

LCMS Method:

Analysis of the extracts was performed on a SCIEX 5500 mass spectrometer interfaced to a Shimadzu Nexera XR UHPLC. The acquisition program was built using scheduled MRM (two product ions for each analyte, on product ion for each internal standard).

TABLE 4 MRM Table: Q1 Q3 DT Transition ID DP EP CP CXP 293.1 171.1 50 IS Benzoylecgonine-D3 200 10 50 12 472.266 400.3 50 IS Buprenorphine-D4 36 10 53 18 282.03 235.12 50 IS EDDP-D3 250 10 60 10 226.012 165.2 50 IS Meprobamate-D7 56 10 11 8 290.105 105.1 50 Benzoylecgonine 1 250 10 60 10 290.105 119 50 Benzoylecgonine 2 200 10 60 8 468.234 396.1 50 Buprenorphine 1 36 10 51 16 468.234 414.2 50 Buprenorphine 2 36 10 45 18 279.122 220.1 50 EDDP 1 250 10 75 14 279.122 187 50 EDDP 2 200 10 65 8 219.116 158 50 Meprobamate 1 170 10 11 16 219.116 55.2 50 Meprobamate 2 140 10 33 14

Analytical Conditions

MS Conditions:

-   SCIEX QTRAP® 5500, Source=ESI -   Positive ion, scheduled MRM -   Source temperature 600° C. -   Desolvation GS1, GS2: 50 -   HPLC gradient profile:

Time % B 0.00 5% 4.00 80%  4.20 100%  4.70 100%  4.71 5% 5.71 5%

-   0.1% Formic acid -   Mobile Phase A (aqueous) -   Mobile Phase B MeOH+0.1% Formic Acid -   Flow Rate : 0.7 mL/min -   Injection Volume 5 ul

LC Conditions:

-   Shimadzu Nexera XR UHPLC -   Column: Raptor™ Biphenyl, 50 mm×2.1 mm, 2.7 um, with Raptor Biphenyl     5 mm guard column, Restek Corp., Bellefonte, PA -   Flow: 700 μL/min -   Column temperature: 40° C. (SPEware column oven) -   Injection volume: 5 μL -   A=0.1% aqueous formic acid; B=0.1% formic acid in Methanol

Results and Conclusions

The following results showed that except for buprenorphine, SPE with the dual stage NBE device provided significantly better recovery than the regular NBE columns with 50 uL of elution solvent.

TABLE 5 Experimental results for four analytes IS % Re- Sample Name Component Name Area Area covery Std R1 Benzoylecgonine 1 786115 552071 100 50 ul elution Benzoylecgonine 1 616656 538764 80 Dual stage HPSCX 50 ul elution Benzoylecgonine 1 599230 571348 74 NBE HPSCX Std R1 Benzoylecgonine 2 201261 552071 100 50 ul elution Benzoylecgonine 2 165762 538764 84 Dual stage HPSCX 50 ul elution Benzoylecgonine 2 163685 571348 79 NBE HPSCX Std R1 Buprenorphine 1 351802 304632 100 50 ul elution Buprenorphine 1 302683 234453 112 Dual stage HPSCX 50 ul elution Buprenorphine 1 343104 254600 117 NBE HPSCX Std R1 Buprenorphine 2 320771 304632 100 50 ul elution Buprenorphine 2 288572 234453 117 Dual stage HPSCX 50 ul elution Buprenorphine 2 332709 254600 124 NBE HPSCX Std R1 EDDP 1 1196197 319077 100 50 ul elution EDDP 1 937635 206197 121 Dual stage HPSCX 50 ul elution EDDP 1 612008 236699 69 NBE HPSCX Std R1 EDDP 2 922362 319077 100 50 ul elution EDDP 2 742065 206197 125 Dual stage HPSCX 50 ul elution EDDP 2 497855 236699 73 NBE HPSCX Std R1 Meprobamate 1 609769 477638 100 50 ul elution Meprobamate 1 428435 445650 75 Dual stage HPSCX 50 ul elution Meprobamate 1 395076 510502 61 NBE HPSCX Std R1 Meprobamate 2 1354992 477638 100 50 ul elution Meprobamate 2 1046582 445650 83 Dual stage HPSCX 50 ul elution Meprobamate 2 1008428 510502 70 NBE HPSCX

In closing, it is to be understood that although aspects of the present specification are highlighted by referring to specific embodiments, one skilled in the art will readily appreciate that these disclosed embodiments are only illustrative of the principles of the subject matter disclosed herein. Therefore, it should be understood that the disclosed subject matter is in no way limited to a particular methodology, protocol, and/or reagent, etc., described herein. As such, various modifications or changes to or alternative configurations of the disclosed subject matter can be made in accordance with the teachings herein without departing from the spirit of the present specification. Lastly, the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention, which is defined solely by the claims. Accordingly, the present invention is not limited to that precisely as shown and described.

Certain embodiments of the present invention are described herein, including the best mode known to the inventor(s) for carrying out the invention. Of course, variations on these described embodiments will become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventor(s) expect skilled artisans to employ such variations as appropriate, and the inventor(s) intend for the present invention to be practiced otherwise than specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described embodiments in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

Groupings of alternative embodiments, elements, or steps of the present invention are not to be construed as limitations. Each group member may be referred to and claimed individually or in any combination with other group members disclosed herein. It is anticipated that one or more members of a group may be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.

Unless otherwise indicated, all numbers expressing a characteristic, item, quantity, parameter, property, term, and so forth used in the present specification and claims are to be understood as being modified in all instances by the term “about.” As used herein, the term “about” means that the characteristic, item, quantity, parameter, property, or term so qualified encompasses a range of plus or minus ten percent above and below the value of the stated characteristic, item, quantity, parameter, property, or term. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical indication should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and values setting forth the broad scope of the invention are approximations, the numerical ranges and values set forth in the specific examples are reported as precisely as possible. Any numerical range or value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Recitation of numerical ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate numerical value falling within the range. Unless otherwise indicated herein, each individual value of a numerical range is incorporated into the present specification as if it were individually recited herein. Similarly, as used herein, unless indicated to the contrary, the term “substantially” is a term of degree intended to indicate an approximation of the characteristic, item, quantity, parameter, property, or term so qualified, encompassing a range that can be understood and construed by those of ordinary skill in the art.

Use of the terms “may” or “can” in reference to an embodiment or aspect of an embodiment also carries with it the alternative meaning of “may not” or “cannot.” As such, if the present specification discloses that an embodiment or an aspect of an embodiment may be or can be included as part of the inventive subject matter, then the negative limitation or exclusionary proviso is also explicitly meant, meaning that an embodiment or an aspect of an embodiment may not be or cannot be included as part of the inventive subject matter. In a similar manner, use of the term “optionally” in reference to an embodiment or aspect of an embodiment means that such embodiment or aspect of the embodiment may be included as part of the inventive subject matter or may not be included as part of the inventive subject matter. Whether such a negative limitation or exclusionary proviso applies will be based on whether the negative limitation or exclusionary proviso is recited in the claimed subject matter.

The terms “a,” “an,” “the” and similar references used in the context of describing the present invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Further, ordinal indicators—such as “first,” “second,” “third,” etc.—for identified elements are used to distinguish between the elements, and do not indicate or imply a required or limited number of such elements, and do not indicate a particular position or order of such elements unless otherwise specifically stated. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein is intended merely to better illuminate the present invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the present specification should be construed as indicating any non-claimed element essential to the practice of the invention.

When used in the claims, whether as filed or added per amendment, the open-ended transitional term “comprising” (along with equivalent open-ended transitional phrases thereof such as “including,” “containing” and “having”) encompasses all the expressly recited elements, limitations, steps and/or features alone or in combination with un-recited subject matter; the named elements, limitations and/or features are essential, but other unnamed elements, limitations and/or features may be added and still form a construct within the scope of the claim. Specific embodiments disclosed herein may be further limited in the claims using the closed-ended transitional phrases “consisting of” or “consisting essentially of” in lieu of or as an amendment for “comprising.” When used in the claims, whether as filed or added per amendment, the closed-ended transitional phrase “consisting of” excludes any element, limitation, step, or feature not expressly recited in the claims. The closed-ended transitional phrase “consisting essentially of” limits the scope of a claim to the expressly recited elements, limitations, steps and/or features and any other elements, limitations, steps and/or features that do not materially affect the basic and novel characteristic(s) of the claimed subject matter. Thus, the meaning of the open-ended transitional phrase “comprising” is being defined as encompassing all the specifically recited elements, limitations, steps and/or features as well as any optional, additional unspecified ones. The meaning of the closed-ended transitional phrase “consisting of” is being defined as only including those elements, limitations, steps and/or features specifically recited in the claim, whereas the meaning of the closed-ended transitional phrase “consisting essentially of” is being defined as only including those elements, limitations, steps and/or features specifically recited in the claim and those elements, limitations, steps and/or features that do not materially affect the basic and novel characteristic(s) of the claimed subject matter. Therefore, the open-ended transitional phrase “comprising” (along with equivalent open-ended transitional phrases thereof) includes within its meaning, as a limiting case, claimed subject matter specified by the closed-ended transitional phrases “consisting of” or “consisting essentially of.” As such, embodiments described herein or so claimed with the phrase “comprising” are expressly or inherently unambiguously described, enabled and supported herein for the phrases “consisting essentially of” and “consisting of.”

All patents, patent publications, and other publications referenced and identified in the present specification are individually and expressly incorporated herein by reference in their entirety for the purpose of describing and disclosing, for example, the compositions and methodologies described in such publications that might be used in connection with the present invention. These publications are provided solely for their disclosure prior to the filing date of the present application. Nothing in this regard should be construed as an admission that the inventors are not entitled to antedate such disclosure by virtue of prior invention or for any other reason. All statements as to the date or representation as to the contents of these documents is based on the information available to the applicants and does not constitute any admission as to the correctness of the dates or contents of these documents.

While aspects of the invention have been described with reference to at least one exemplary embodiment, it is to be clearly understood by those skilled in the art that the invention is not limited thereto. Rather, the scope of the invention is to be interpreted only in conjunction with the appended claims and it is made clear, here, that the inventor(s) believe that the claimed subject matter is the invention. 

What is claimed is:
 1. An apparatus for extracting an analyte from a liquid sample comprising: a first microcolumn comprising a first passage, a flow distributor layer extending across the first passage; and a second microcolumn comprising a second passage, an extraction layer extending across the second microcolumn; wherein, the first microcolumn positioned above and in series with the second microcolumn with the first passage in fluid communication with the second passage.
 2. The apparatus of claim 1, wherein the first passage of the first microcolumn comprises a first full diameter bed region and a first reduced diameter bed region, and the second passage of the second microcolumn comprises a second full diameter bed region and a second reduced diameter bed region.
 3. The apparatus of claim 2, wherein the flow distributor layer is located in the first full diameter bed region of the first microcolumn, and the extraction layer is located in the second reduced diameter bed region of the second microcolumn.
 4. The apparatus of claim 3, wherein the flow distributor layer is layered with a first compression layer to form a first layered construction, and the extraction layer is layered with a second compression layer to form a second layered construction.
 5. The apparatus of claim 1, wherein the flow distributor layer is layered with a first compression layer to form a first layered construction.
 6. The apparatus of claim 1, wherein the extraction layer is layered with a second compression layer to form a second layered construction.
 7. The apparatus of claim 1, further comprising a plurality of first microcolumns arranged in a first array and a plurality of second microcolumns arranged in a second array, the first array stacked atop the second array such that each of the plurality of first microcolumns is aligned with each of the plurality of second microcolumns.
 8. The apparatus of claim 6, wherein the plurality of the first microcolumns are arrangeable on a first base to form the first array and the plurality of the second microcolumns are arrangeable on a second base to form the second array.
 9. The apparatus of claim 7, wherein a first top plate holds each of the first microcolumns in parallel and a second top plate holds each of the second microcolumns in parallel.
 10. An apparatus for extracting an analyte from a liquid sample comprising: a plurality of first microcolumns arranged in a first array, each of the plurality of first microcolumns comprising a first passage, a flow distributor layer extending across the first passage; and a plurality of second microcolumns arranged in a second array, each of the plurality of second microcolumns comprising a second passage, an extraction layer extending across the second microcolumn; wherein, the first array is stacked atop the second array such that each of the plurality of first microcolumns is aligned with each of the plurality of second microcolumns; and wherein each of the plurality of first microcolumns is positioned above and in series with each of the plurality of second microcolumn with the first passage in fluid communication with the second passage in each instance.
 11. The apparatus of claim 10, wherein the plurality of the first microcolumns are arrangeable on a first base to form the first array and the plurality of the second microcolumns are arrangeable on a second base to form the second array.
 12. The apparatus of claim 11, wherein a first top plate holds each of the first microcolumns in parallel and a second top plate holds each of the second microcolumns in parallel.
 13. The apparatus of claim 11, wherein the first passage of the first microcolumn comprises a first full diameter bed region and a first reduced diameter bed region, and the second passage of the second microcolumn comprises a second full diameter bed region and a second reduced diameter bed region.
 14. The apparatus of claim 13, wherein the flow distributor layer is located in the first full diameter bed region of the first microcolumn, and the extraction layer is located in the second reduced diameter bed region of the second microcolumn.
 15. The apparatus of claim 14, wherein the flow distributor layer is layered with a first compression layer to form a first layered construction, and the extraction layer is layered with a second compression layer to form a second layered construction.
 16. The apparatus of claim 10, wherein the flow distributor layer is layered with a first compression layer to form a first layered construction.
 17. The apparatus of claim 10, wherein the extraction layer is layered with a second compression layer to form a second layered construction. 